With the increased drilling for oil and gas in offshore locations and particularly in water too deep for divers atmospheric chambers have been installed on wellheads on the floor of the ocean. These chambers allow the crew to be delivered to the location in a diving bell or a submarine and to perform completion, connection and workover tasks in an environment in which they can work efficiently for reasonable periods of time.
One of the problems with these chambers has been the making of a connection through the chamber wall from the wellhead production flowlines within the chamber to a pipeline on the exterior of the chamber. Prior to the present invention efforts to bring a pipeline into communication with the chamber have been attempted with cables and winches. The R. R. Roesky et al U.S. Pat. No. 3,482,410, the A. J. Bergquist et al U.S. Pat. No. 3,795,115, the J. DeJohn U.S. Pat. No. 3,967,462, the J. P. Oliver U.S. Pat. No. 3,835,655, the B. J. Watkins et al U.S. Pat. No. 3,260,270, the W. Brown et al U.S. Pat. No. 3,592,014 and the R. A. Marquaire et al U.S. Pat. No. 4,004,635 are examples of the use of cables and winches to pull pipelines into connection with an undersea installation. The L. E. Williams et al U.S. Pat. No. Re. 27,340 discloses an underwater connector between a pipeline and a production wellhead in which yokes engage aligned hubs and pull them together for securing by a clamp remotely operated mechanically by a drill string extending to the surface.
Difficulties have been encountered with the use of cables and winches and in some instances connections could not be made. Further, the christmas tree could not be installed and tested in some of these prior chamber structures until the flowline had been pulled in by the cable. Thus, the christmas tree had to be installed and tested at the sea bottom. Also, such prior art connectors could not be lowered and retrieved independently of the chamber to which they are connected.